Place the vinegar, sugar and soy sauce in a small saucepan over medium heat. Cook, stirring, until the sugar dissolves. Simmer for 5 minutes or until the mixture is slightly reduced. Add the onion and capsicum and set aside to cool slightly.

Step 2

Place the combined flour on a plate. Add the fish and toss to coat. Shake off any excess. Add oil to a large frying pan to come 1cm up the side of the pan. Heat over medium-high heat. Add the fish and cook for 2 minutes, turning halfway through cooking, or until cooked through. Use a slotted spoon to transfer the fish to a plate lined with paper towel. Transfer to a heatproof bowl and pour over the vinegar mixture. Stir to combine. Set aside for 1 hour to develop the flavours.